Not per se "Illegal", just looked down upon on how effective it works. It's not recommended you do this, since you need to kill OTHER survivors, but if you're camping a Super-Altruistic survivor, or you know that a survivor is nearby, go and do that.

There have been times where I have camped survivors who are being toxic towards me, but I don't always utilize it. However, unless you specifically target one survivor over the course of multiple sessions, it is reportable and could result in a ban if repeated. But if it's just for one game, the devs won't even bat an eye. I had a group of survivors once tell me that hatch tending was bannable, and yet I could find no evidence of this whatsoever. It was likely just a survivor complaining about not being able to escape due to it being a hatch standoff.

If you're the killer, you know where the hatch is, and you make it there before the survivor, you have every right to make it a standoff to try and prevent the survivor from escaping. If you are the survivor and you discover the hatch has been secured by the killer, then go work on a generator to lure them away from the hatch. If the killer realizes you aren't gonna try going through the hatch, it may force them to leave, making the hatch available. It's not a very good strategy, but it's not bannable.

But I will say this. Try not to camp if as all possible. Only use it if there are no other options left.

I used a survivor load out against a camper. I used saboteur (I know it’s weak, but wait) Empathy, so I see injured survivors, borrowed time, and decisive strike. I broke a hook with the killer right there carrying a survivor I got a borrowed time save, twice, thanks to the new buff. I kited them for ages and when they caught me, I DSed off them and ran off to the Hatch.

Also, why do survivors wait at the hatch for every one to escape? I once was kiting around the closed Hatch and ended up dying because the other survivors were waiting for me.

It is not illegal. There are two cases where I camp/facecamp. The first is if I am doing a daily to sacrifice 2 survivors, (which is meaning I don't really care about the match. The second is if the other survivors are being overly and stupidly altruistic. When all three other survivors have gathered around befor I even hook the one in my arms then why bother leaving? They are not working on engines and are comeing to me themselves.